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2. Trauma MCQs

Practice Set 529 of 640

This practice set contains high-yield board review questions covering key concepts in 2. Trauma. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 10561

Topic: 2. Trauma

An orthopedic randomized controlled trial evaluates a new fracture fixation plate against the gold standard. The study concludes there is no statistically significant difference in union rates (p = 0.08). However, independent long-term data later proves the new plate actually has a higher nonunion rate. Which statistical error was committed in the original trial?

. Type I error
. Type II error
. Selection bias
. Observer bias
. Confounding error

Correct Answer & Explanation

. Type I error

Explanation

A Type II error (false negative) occurs when a study fails to reject a false null hypothesis—meaning the study finds no difference when a true difference actually exists. This is often due to an inadequate sample size (low power). A Type I error is a false positive.

Question 10562

Topic: Lower Extremity Trauma



According to the fundamental biomechanical principles of intramedullary nailing, if the working length of a solid intramedullary nail is doubled, its torsional rigidity is mathematically altered by what factor?

. Decreased by a factor of 2
. Decreased by a factor of 4
. Increased by a factor of 2
. Increased by a factor of 4
. Increased by a factor of 16

Correct Answer & Explanation

. Decreased by a factor of 2

Explanation

The torsional stiffness (rigidity) of a solid cylinder (like an intramedullary nail) is inversely proportional to its working length (L) and directly proportional to the polar moment of inertia, which relies on the fourth power of its radius (r^4). Because torsional rigidity = (G * J) / L, doubling the working length (L) decreases the overall torsional rigidity by half (a factor of 2).

Question 10563

Topic: 2. Trauma

When applying a bridge plate to a comminuted diaphyseal fracture, increasing the 'working length' (the distance between the innermost screws on either side of the fracture) has what primary biomechanical effect?

. Increases the axial stiffness of the construct
. Decreases the relative strain at the fracture site for a given load
. Increases the risk of screw pull-out
. Eliminates interfragmentary motion completely
. Shifts the biological response to primary bone healing

Correct Answer & Explanation

. Increases the axial stiffness of the construct

Explanation

Increasing the working length of a plate decreases the overall construct stiffness, allowing bending forces to distribute over a longer segment. This permits some beneficial interfragmentary motion while significantly decreasing the relative strain at the fracture gap compared to a short working length, thereby promoting secondary bone healing through callus formation.

Question 10564

Topic: Lower Extremity Trauma

When replacing a solid intramedullary nail with a hollow intramedullary nail of the identical outer diameter, how is the torsional rigidity of the implant mathematically affected?

. It increases significantly
. It remains unchanged
. It decreases proportional to the inner radius to the fourth power
. It decreases proportional to the inner radius squared
. It decreases proportional to the length of the nail

Correct Answer & Explanation

. It increases significantly

Explanation

Torsional rigidity is proportional to the polar moment of inertia. For a hollow cylinder, it is proportional to (outer radius^4 - inner radius^4). Thus, hollowing the nail decreases its rigidity by a factor proportional to the inner radius^4.

Question 10565

Topic: 2. Trauma

A 65-year-old female sustains a fracture of the distal radius. Radiographs reveal a volar marginal intra-articular fracture fragment that is displaced proximally and volarly, carrying the carpus with it (Volar Barton's fracture). The continued attachment of which of the following stout ligaments is responsible for pulling the carpus in this direction?

. Dorsal radiocarpal ligaments
. Radioscaphocapitate and long radiolunate ligaments
. Scapholunate interosseous ligament
. Triangular fibrocartilage complex
. Ulnocapitate ligament

Correct Answer & Explanation

. Dorsal radiocarpal ligaments

Explanation

A Volar Barton's fracture is a shear fracture of the volar lip of the distal radius. The strong volar extrinsic radiocarpal ligaments (specifically the radioscaphocapitate, long radiolunate, and short radiolunate ligaments) originate on this volar marginal fragment. When the fragment displaces, these intact ligaments tether the carpus, causing volar subluxation of the entire carpus along with the bone fragment.

Question 10566

Topic: 2. Trauma

A 24-year-old male presents with persistent wrist pain 6 months after a fall. Radiographs demonstrate a proximal pole scaphoid nonunion with sclerosis and avascular necrosis.

What is the most appropriate surgical treatment?

. Open reduction and internal fixation with a headless compression screw alone
. Proximal row carpectomy
. Vascularized bone grafting and internal fixation
. Four-corner fusion
. Radial styloidectomy

Correct Answer & Explanation

. Open reduction and internal fixation with a headless compression screw alone

Explanation

Proximal pole scaphoid nonunions with AVN have a poor healing rate with non-vascularized grafts alone. Vascularized bone grafts (e.g., 1,2-ICSRA or medial femoral condyle) combined with rigid fixation are indicated to restore perfusion and promote union.

Question 10567

Topic: 2. Trauma

How many distinct fascial compartments are typically recognized in the human hand when evaluating for compartment syndrome?

. 4
. 7
. 10
. 14
. 18

Correct Answer & Explanation

. 4

Explanation

The hand contains 10 distinct compartments: 4 dorsal interosseous, 3 volar interosseous, the thenar compartment, the hypothenar compartment, and the adductor pollicis compartment.

Question 10568

Topic: 2. Trauma

A 10-year-old boy presents to the emergency department after his finger was caught in a door. Examination reveals a laceration across the dorsal nail fold of the middle finger, the nail plate displaced dorsal to the eponychium, and a hyperflexed posture of the distal phalanx. Radiographs show a displaced Salter-Harris I fracture of the distal phalanx. What is the most appropriate management of this Seymour fracture?

. Closed reduction and buddy taping, leaving the nail intact
. Nail trephination and splinting
. Immediate operative amputation due to neurovascular compromise
. Removal of the nail plate, irrigation, reduction of the fracture, repair of the nail bed, and possible pinning
. Prescription of oral antibiotics and outpatient follow-up in 2 weeks

Correct Answer & Explanation

. Closed reduction and buddy taping, leaving the nail intact

Explanation

A Seymour fracture is a juxta-epiphyseal (Salter-Harris I or II) fracture of the distal phalanx, classically associated with a nail bed laceration, making it an open fracture. The germinal matrix is frequently avulsed and interposed in the fracture site, preventing closed reduction. Proper management mandates removal of the nail plate, thorough irrigation and debridement (as it is an open fracture), reduction of the fracture, repair of the nail bed, and stabilization (often with a K-wire).

Question 10569

Topic: Pelvic & Acetabular Trauma

A trauma patient undergoes a pelvic series after a high-speed motor vehicle collision.

On an obturator oblique radiograph (Judet view) of the pelvis, which two osseous acetabular structures are best profiled?

. Anterior column and posterior wall
. Posterior column and anterior wall
. Anterior column and anterior wall
. Posterior column and posterior wall
. Iliac wing and obturator ring

Correct Answer & Explanation

. Anterior column and posterior wall

Explanation

The Judet views are orthogonal X-rays used to evaluate acetabular fractures. The obturator oblique view (pelvis rotated 45 degrees away from the affected side) best profiles the anterior column and the posterior wall of the acetabulum. Conversely, the iliac oblique view profiles the posterior column and the anterior wall.

Question 10570

Topic: 2. Trauma

A 24-year-old marathon runner develops severe lateral and posterior leg pain, concerning for exertional compartment syndrome. Which of the following structures is exclusively located within the deep posterior compartment of the leg?

. Plantaris
. Peroneus brevis
. Flexor hallucis longus
. Soleus
. Superficial peroneal nerve

Correct Answer & Explanation

. Plantaris

Explanation

The deep posterior compartment of the leg contains the flexor hallucis longus, flexor digitorum longus, tibialis posterior, and the posterior tibial artery and tibial nerve. The soleus and plantaris are in the superficial posterior compartment. The peroneus brevis is in the lateral compartment.

Question 10571

Topic: 2. Trauma

Avascular necrosis (AVN) is a well-known complication of proximal pole scaphoid fractures. The primary intraosseous blood supply to the proximal pole of the scaphoid enters the bone at which anatomical location?

. Volar distal pole
. Dorsal ridge
. Tuberosity
. Proximal articular surface
. Volar waist

Correct Answer & Explanation

. Volar distal pole

Explanation

The scaphoid receives its primary blood supply from branches of the radial artery that enter along the dorsal ridge (distal to the waist) and travel in a retrograde fashion to supply the proximal pole. Because of this retrograde flow, fractures at the waist or proximal pole highly compromise the blood supply to the proximal segment, predisposing it to nonunion and AVN.

Question 10572

Topic: Lower Extremity Trauma

Meniscal tears are a common knee pathology. In basic science review of meniscal anatomy, which of the following statements is true regarding the medial meniscus compared to the lateral meniscus?

. The medial meniscus is more circular in shape
. The medial meniscus is more mobile
. The medial meniscus covers a larger percentage of its respective tibial plateau
. The medial meniscus is firmly attached to the deep medial collateral ligament
. The lateral meniscus lacks an attachment to the joint capsule

Correct Answer & Explanation

. The medial meniscus is more circular in shape

Explanation

The medial meniscus is larger, more 'C'-shaped (semilunar), less mobile, and covers less of the medial tibial plateau surface area compared to the lateral meniscus (which is more 'O'-shaped and covers more of the lateral plateau). The medial meniscus is firmly anchored to the joint capsule and the deep medial collateral ligament, restricting its mobility and making it more prone to injury.

Question 10573

Topic: Lower Extremity Trauma

An orthopedic surgeon is performing a posterolateral approach to the tibial plateau. To adequately expose the joint, the fibular collateral ligament may need to be visualized. What nerve is most at risk during the distal extent of this exposure, and where does it typically cross the fibula?

. Common peroneal nerve; posterior to the fibular head
. Common peroneal nerve; wraps anteriorly around the fibular neck
. Deep peroneal nerve; pierces the anterior intermuscular septum
. Tibial nerve; passes deep to the soleus bridge
. Superficial peroneal nerve; runs along the lateral border of the fibula

Correct Answer & Explanation

. Common peroneal nerve; posterior to the fibular head

Explanation

The common peroneal nerve travels posterior to the biceps femoris and wraps around the fibular neck, placing it at high risk during posterolateral knee approaches.

Question 10574

Topic: 2. Trauma

During a lateral approach to the fibula for a distal third fracture, a surgeon must be careful to avoid the superficial peroneal nerve. Where does this nerve typically pierce the deep fascia to become subcutaneous?

. At the fibular neck
. 10-12 cm proximal to the tip of the lateral malleolus
. 5 cm proximal to the fibular head
. Posterior to the lateral malleolus
. Through the anterior intermuscular septum at the joint line

Correct Answer & Explanation

. At the fibular neck

Explanation

The superficial peroneal nerve typically pierces the deep fascia of the lateral compartment approximately 10-12 cm proximal to the tip of the lateral malleolus to become subcutaneous.

Question 10575

Topic: 2. Trauma

During open reduction and internal fixation of a scaphoid nonunion via a dorsal approach, the surgeon must carefully preserve the blood supply to the proximal pole. What is the primary arterial supply to the proximal pole of the scaphoid?

. Volar branches of the radial artery entering the distal pole
. Dorsal carpal branch of the radial artery entering the dorsal ridge
. Anterior interosseous artery branches entering the proximal pole directly
. Ulnar artery branches running through the radiocarpal ligaments
. Superficial palmar arch branches entering the scaphoid tubercle

Correct Answer & Explanation

. Volar branches of the radial artery entering the distal pole

Explanation

The primary blood supply to the scaphoid is retrograde, originating from the dorsal carpal branch of the radial artery which enters the dorsal ridge. This retrograde flow makes the proximal pole highly susceptible to avascular necrosis after fractures.

Question 10576

Topic: Pelvic & Acetabular Trauma

A trauma patient is evaluated with a pelvic radiograph series after a fall from a height. On an iliac oblique radiograph (Judet view), which two osseous structures of the acetabulum are best profiled?

. Anterior column and posterior wall
. Posterior column and anterior wall
. Anterior column and anterior wall
. Iliac wing and obturator ring
. Ischial spine and sacral ala

Correct Answer & Explanation

. Anterior column and posterior wall

Explanation

The iliac oblique view is obtained with the patient rotated 45 degrees toward the uninjured side. This view best profiles the posterior column and the anterior wall of the acetabulum.

Question 10577

Topic: 2. Trauma

An axial CT of a distal tibia pilon fracture demonstrates a classic 3-part articular fragment pattern. The anterolateral (Tillaux-Chaput) fragment is avulsed by its attachment to which critical ligament?

. Anterior inferior tibiofibular ligament (AITFL)
. Posterior inferior tibiofibular ligament (PITFL)
. Deltoid ligament
. Interosseous membrane
. Calcaneofibular ligament

Correct Answer & Explanation

. Anterior inferior tibiofibular ligament (AITFL)

Explanation

The anterolateral fragment of the distal tibia (Tillaux-Chaput fragment) represents an avulsion of the anterior inferior tibiofibular ligament (AITFL). The posterolateral fragment (Volkmann) is associated with the PITFL.

Question 10578

Topic: Pelvic & Acetabular Trauma

A patient presents with a suspected anterior column acetabular fracture. Which standard radiographic view best profiles the anterior column of the acetabulum and the posterior edge of the iliac wing?

. AP Pelvis
. Judet Iliac Oblique
. Judet Obturator Oblique
. Inlet view
. Outlet view

Correct Answer & Explanation

. AP Pelvis

Explanation

The Judet iliac oblique view profiles the anterior column and the posterior wall of the acetabulum. The obturator oblique view profiles the posterior column and the anterior wall.

Question 10579

Topic: 2. Trauma
A 35-year-old male presents after an MVC with a systolic BP of 75 mmHg. Heart rate is 135 bpm. FAST scan is negative. Pelvic radiograph shows an APC-III pelvic ring injury. A pelvic binder is applied. Fluid resuscitation is initiated but his BP remains 80 mmHg. What is the most appropriate next step in management?
. CT abdomen and pelvis with IV contrast
. Pelvic angiography with embolization
. Pre-peritoneal pelvic packing and external fixation
. Laparotomy
. Retrograde urethrogram

Correct Answer & Explanation

. Pre-peritoneal pelvic packing and external fixation

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST (ruling out intra-abdominal bleeding), the source of bleeding is likely the pelvis (venous or arterial). If the patient remains unstable despite a pelvic binder and initial fluid resuscitation, emergent mechanical stabilization (e.g., external fixation) and pre-peritoneal pelvic packing (PPP) is indicated. Currently, ATLS/AAOS guidelines support PPP + Ex-Fix as a rapid, definitive initial step in the operating room for venous bleeding (which accounts for ~80% of pelvic hemorrhage), often followed by angio if bleeding persists.

Question 10580

Topic: 2. Trauma

Which of the following radiographic findings is most predictive of avascular necrosis (AVN) following a complex 4-part proximal humerus fracture?

. Disruption of the medial periosteal hinge (calcar length < 8 mm)
. Greater tuberosity displacement > 5 mm
. Varus angulation of 15 degrees
. Involvement of the bicipital groove
. Shortening of the surgical neck > 10 mm

Correct Answer & Explanation

. Disruption of the medial periosteal hinge (calcar length < 8 mm)

Explanation

Hertel et al. described radiographic predictors for humeral head ischemia (and subsequent AVN) in proximal humerus fractures. The most significant predictors include a medial metaphyseal head extension (calcar length) of less than 8 mm, disruption of the medial periosteal hinge, and basicervical fracture patterns. Disruption of the medial periosteal hinge eliminates the protection to the ascending branch of the anterior humeral circumflex artery and intraosseous collateral vessels.

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